The mass spectra of phenyl methyl ethers. II. Polycyclic compounds

Abstract

The fragmentation of the aryl methyl ether grouping on electron impact has been studied in a number of naphthalene, phenanthrene, stilbene, and tolane derivatives. In addition to the known aryl-oxygen fission with migration of one hydrogen atom (loss of formaldehyde), and alkyl- oxygen fission (loss of a methyl radical), an examination of metastable ions has indicated two new pathways which may occur in special circumstances. The first was found unequivocally only in the single example of 9-methoxyphenanthrene and may be related to the stability of the resultant fluorenyl ion. The second was simple aryl-oxygen fission without rearrangement and occurred in those cases where the corresponding hydrocarbon showed a strong P - 1 ion on electron impact. However, this feature in the hydrocarbon does not always ensure loss of a methoxy radical from the methoxy derivative, because the possibility of forming a stable quinonoid ion may make loss of a methyl radical the preferred course.